Similar presentations

3
Hormone chemistry and Action Are chemically composed of either: (p. 516 in Saladin) –Ring structures = steroids –Polypeptides = ACTH, TSH, FSH, LH, oxytocin, insulin, etc. –Monoamines = dopamine, thryoxine (T3/T4) At their target cell, they may diffuse through the cell membrane and bind to a receptor site in the cytoplasm or nucleus (steroid hormones), or they may they may bind to a receptor site on the cell membrane (water- soluble hormones) and activate a first messenger (e.g. adenylate cyclase) which, in turn, activates a second messenger (cyclic AMP).

4
Endocrine System vs Autonomic Nervous System 1. The endocrine system releases chemical messengers (hormones) into the blood. The autonomic nervous system communicates by nerve impulses with effectors. 2. The endocrine system acts relatively slowly as compared to the autonomic nervous system.

9
The Hypothalamus Location: directly below the thalamus in the diencephalon of the brain. It lies between the optic chiasm anteriorly and the mammillary bodies posteriorly and is inferior to the third ventricle. Structure: Composed of several groups of nuclei, the hypothalamus controls the endocrine system as well as the autonomic nervous system and produces regulatory hormones that regulate the release of numerous pituitary hormones. It also produces the hormones of the posterior pituitary.

16
Posterior Pituitary Hormones ADH an Oxytocin are secreted by neurosecretory cells in the paraventricular and supraoptic nuclei of the hypothalamus and are transported to posterior pituitary via hypothalamohypophyseal tract.

17
Neurohypophyseal Hormones Antidiuretic hormone (ADH) – produced by supraoptic nuclei in the hypothalamus. –Consists of 9 amino acids –Reduces the excretion of water by kidney collecting ducts; increases cuddling and grooming behavior. Oxytocin – produced by the paraventricular nuclei in the hypothalamus –Consists of 9 amino acids, but differs from ADH. –Induces smooth muscle contraction; increases cuddling and grooming behavior.

19
Thyroid gland Location: largest pure endocrine gland in adults ~ gms. and located adjacent to trachea inferior to larynx. Structure: Butterfly shaped with two lobes joined by an isthmus. ~ 50% of people have a pyramidal lobe growing upward off of isthmus. Gross Anatomy: Bulbous at inferior end and tapers superiorly. - Thyroid is highly vascular via thyroidal arteries. Cellular Anatomy: Composed of sacs of thyroid follicular cells and lined with simple cuboidal or simple squamous epithelium that is filled with protein rich colloid (thyroglobulin).

20

21
Thyroid gland Follicular cells produce tri-iodo thyronine (T3) and thyroxine (T4) which are stored in thyroglobulin. –Target cells are every cell and tissue in the body Parafollicular or “C” cells found between follicular cells in the thyroid gland produce calcitonin which keeps blood Ca++ levels within the normal range by depositing excess Ca++ in the bones and teeth. –Target cells are osteoblasts in bone –Has no demonstrable function in adults, most active in fetus, infants and adolescents.

31
Ovaries Primary sex organs of females Located retroperitoneal in the abdominal cavity lateral to the uterus and at the proximal end of the uterine tubes (fallopian tubes). Pair of almond shaped organs ~ 3 cm x 1.5 cm x 1 cm. Produce female sex hormones (estrogen and progesterone) and contain ova. More about the ovaries in reproduction.

35
Thymus Located in mediastinal space of the thoracic cavity deep to sternum and supeficial to the pericardium. Produces several hormones amongst which are thymosin, thymopoietin, and IGF-1. Stimulates the maturation of T- lymphocytes Largest size occurs at puberty and thereafter diminishes in size as one gets older. By the age of 50 it is ~ ¼ its original size. Largest size occurs at puberty and thereafter diminishes in size as one gets older. By the age of 50 it is ~ ¼ its original size.

36
Thymus

37
Pineal gland or “epiphysis cerebri” Part of the epithalamus in the brain Contains neurons, glial cells and pinealocytes which produce and secrete melatonin. Melatonin regulates the circadian cycle as well as slows the maturation of sperm and ova by inhibiting FSH and LH release from the adenohypophysis.